Development of GaN HEMTs Fabricated on Silicon, Silicon-on-Insulator, and Engineered Substrates and the Heterogeneous Integration

Abstract

GaN HEMT has attracted a lot of attention in recent years owing to its wide applications from the high-frequency power amplifier to the high voltage devices used in power electronic systems. Development of GaN HEMT on Si-based substrate is currently the main focus of the industry to reduce the cost as well as to integrate GaN with Si-based components. However, the direct growth of GaN on Si has the challenge of high defect density that compromises the performance, reliability, and yield. Defects are typically nucleated at the GaN/Si heterointerface due to both lattice and thermal mismatches between GaN and Si. In this article, we will review the current status of GaN on Si in terms of epitaxy and device performances in high frequency and high-power applications. Recently, different substrate structures including silicon-on-insulator (SOI) and engineered poly-AlN (QST®) are introduced to enhance the epitaxy quality by reducing the mismatches. We will discuss the development and potential benefit of these novel substrates. Moreover, SOI may provide a path to enable the integration of GaN with Si CMOS. Finally, the recent development of 3D hetero-integration technology to combine GaN technology and CMOS is also illustrated.

Influence of a thick nitride layer on transmission loss in GaN-on-3C-SiC/low resistivity Si

“…The GaN-based devices offer excellent superiority in highpower and high-frequency technologies because of their capability to deliver high power densities at both microwave and millimeter-wave (mmW) frequencies along with high electron saturation velocities [1][2][3][4][5][6][7][8][9][10][11]. For GaN-based RF power devices, SiC is usually preferable owing to high thermal conductivity, high electrical resistivity, and very low mismatch to GaN [12][13][14][15]. However, SiC substrates are expensive and unavailable in large size wafers, which limits the cost-effective scaling of the technology [16][17][18].…”

Investigation on the Thermal Characteristics of Enhancement-Mode p-GaN HEMT Device on Si Substrate Using Thermoreflectance Microscopy

“…In recent years, the enhancement-mode p-GaN HEMTs on silicon substrate have been widely used in the power converters because of its superior performances [ 2 , 3 ]. The p-GaN HEMTs have been demonstrated to have ten times greater output power density ( P ) than that of the conventional Si devices due to the high field strength of GaN material and the polarization-effect-induced high-density high-mobility 2-D electron gas (2DEG) [ 4 , 5 , 6 ]. However, for the high-power density application, the junction temperature ( T J ) of the device can exceeds 150 °C, which has demonstrated detrimental consequences on the performance and reliability of the GaN devices [ 7 , 8 ].…”

Reduction in RF Loss Based on AlGaN Back-Barrier Structure Changes

“…The crystal quality of GaN thin film grown on SiC substrate is quite excellent. However, the cost of the SiC substrate is high, and the wafer size is small (3 to 4 inches), which are obstacles to the industrialization of the GaN HEMT device [6,7]. Compared with SiC substrate, Si substrate has a low price and a large wafer size (≥6 inches), which means that a GaN HEMT device based on Si substrate has some advantage in industrialization.…”